Protein S Activity
Also known as: Protein S, Functional
Use
Measurement of Protein S activity is used in the evaluation of thrombotic risk due to inherited or acquired deficiencies or dysfunctions in Protein S. Such deficiencies may result in impaired anticoagulant activity and predispose individuals to venous thromboembolism. The Protein S Activity assay helps clinicians differentiate between functional deficiencies and quantitative abnormalities in Protein S, aiding diagnostic and therapeutic decision-making.
Special Instructions
No fasting is required prior to collection. Avoid warfarin therapy for 2 weeks and heparin therapy for 2 days before the specimen is collected. Patients should consult their physician before stopping any medications.
Limitations
Warfarin or heparin therapy may affect results if cessation intervals are not maintained. Plasma samples must be properly prepared (e.g., platelet-free) to avoid under-recovery of Protein S activity. Inaccurate specimen handling, platelet contamination, or improper anticoagulant therapy management may lead to unreliable results.
Methodology
Other
Biomarkers
Result Turnaround Time
7-10 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
Not provided
Minimum Volume
Not provided
Collection Instructions
Draw blood in a light blue-top tube containing 3.2% sodium citrate, mix gently by inverting 3–4 times, centrifuge 15 minutes at 1500 g within one hour of collection. Using plastic pipette, remove plasma, avoiding the WBC/platelet buffy layer.
Patient Preparation
No fasting required; discontinue warfarin 2 weeks before and heparin 2 days before collection, per physician guidance.
Causes for Rejection
Platelet contamination; hemolysis
Other tests from different labs that may be relevant